Periscopic sextant



Dec. 25, 1951 v. E. CARBONARA 2,579,903

PERISCOPIC SEXTANT Filed June 16, 1948 6 Sheets-Sheet l INVENTUR. Vzcf for Jfd'arioward.

Dec. 25, 1951 v. E. CARBONARA PERISCOPIC SEXTANT Filed June 16, 1948 6 Sheets-Sheet 2 INVEN TOR. {0 CarZarrara Dec. 25, 1951 ARBONARA 2,579,903

PERISGOPIC SEXTANT Filed June 16, 1948 a Sheets-Sheet 5 Filed June 16, 1948 Dec. 25, 1951 v CARBONARA 2,579,903

PERISCOPIC SEXTANT 6 Sheets-$heet 4 INVENTOR. z'cz ar IC'arZavara.

Dec. 25, 1951 v. E. CARBONARA PERISCOPIC SEXTANT 6 Sheets-Sheet 5 Filed June 16, 1948 INVENTOR. WCZa/ l'arzan'ara BY/fl Dec. 25, 1951 v, CARBQNARA 2,579,903

' PERISCOPIC SEXTANT Filed June 16, 1948 6 Sheets-Sheet 6 IN V EN T 0R. Wc for lC'arZaflara,

17' 7a P/VIX Patented Dec. 25, 1951 by me's'ne assignments, to Kcllsman Instrument Corporation, Elmh-urst, N. Y., a corporation of New York Application June '16, 1948, SerialNo.'33,345

2 Claims. (Cl.-" 88'2l7) This invention relates to aperiscopic sextant adapted to be projected-through the'skinof an aircraft to permit a navigator to make-observa-- tions from within the cabin.

object of the invention is to *provide a periscopic sextant with a simple and accurate me-- -chanical connection between the operating knob andthe index prism.

Another'obj'ect of the iiiventionis the'p'rovision of a p'eriscopic sextant in accordance with the preceding object inwhich'thereis provided adjusting 'means to properly correlate the rotation of the prism and the instrument counter in'dica- 'tion.

Another object of the invention is the provision of a periscopic sextant in accordance with the preceding object in which the adjusting means will not onlytake-care'of cumulative mechanical error in the gear portion of the 1 mechanical operating train, but will also serve'to reduce'any error which may be present in theprism surfaces.

Another object of the invention-is the provision of a periscopic "sextant with a :mechanicaloperating train between the index prism and the operating knob which does not require the presence 'o'f gearing at the "index prism s'o that a' minimum sized head may be used with 'a corresponding small opening through which itmay "be-passed.

Other objects and features of the" invention will be readily apparent to those skillediini theiart from the specification and appended drawings illustrating c'e'r-tain preferred. l embodiments 1 in which:

Figure 1 is :a front elevational" view it of 'a aperiscopic sextant :in accordance with the present invention.

Figure 2 i's 'a-diagrammatic representation of the optical system through the instrument s'how ing 'both the main optical system through the instrument and the optically produced. artificial h'orizon. I

Figure '3 is a sectional wiew through 'the imam body 'portion of the instrument.

Figure "4 a-sectional view through'nthe 'tperiscope-portion of the -instrument.

Figure 5 is a detailed view of the body bf the index prism in the periscope-h'ead on line V--V of Figureil r v Figure 6 is a sectional view showing apart of the operating mechanism.

Figure 7 is ase'ctional view on the line VIL-VII of Figure 6.

4 Figure 8 i's'a sectional View on the line VIII- VIII #of Figure 6; b l

m'tneelevationai viewer-leisure-isthe sextant shown as comprising a main body portion 2 and atubular periscope section 'I. "The main body 'portionincludes the operating knob 3 and-a second high speed operating knob 4 for rotating the index prism and the counter 5. The eyepiece for the observer is indicated at'fi.

The optical system illustrated inFigure 2 comprises an entrance window I through which-the light from the observed body passes to the index *gpris'm 8 and thence through first and second objective lenses Sand l'l andobjective-field lens i2. From the objective field lens 12, the "light passes throughan erecting system formed by th'e lenses i3, M, through a window I 5 and thence to a prism i3 from whence the lightis reflected and passes through a partially reflecting pellicle 'i-lto form a real image of the observed bodyin the focal plane of the erecting system at whichris disposed theeyepiece 'field lens 8. The eyepiece through which the image is observed further. includes an intermediate field lens [9 and. anieye lensZI.

The artificial 'horizon is obtained by the light of an illuminated line reflected from a pendulous mirror. The light source is indicated at 22,lpassing throughcondenser lenses 23 and 24 and then through a filter and reticle "25 which has a thin line thereon through which light from the source '22. passes. Light from the illuminated line passes through the .pellicle I! and a lens 26 to the refleeting surface of a lpendulous mirror 21 from which. thelightis reflected again through thelens -26 tothelpellicle .I'lfrom WhiChit is reflectedlinto the.optical path from the observed body. The lens 26 has its focus coincident with that ofthe opticahsystem of the sextant so that it forms a real image on the illuminated line at the t field lens'1'8. 'With the magnifying ocular focusedupo'n thereal images of the observed body and illuminated line, it views them projected to infinity. Thealtitudenangleof a-celestial body is obtained when the instrument is. adjusted so that the images of the body and the illuminated line coin cide; as will be explained.

Referring (to Figures 4 and 5, it will be :seen that the periscopesection of the instrument i's comprised of an outer tube 28 within which is disposed asecond tube 29 carrying thEOPtiCSJOf the periscope portion of the sextant. At "the head of the :peris'cope there is provided the entrance window 1 and index prism 8 previously described. At the upper end of the tubular portion 129 is mounted a platform 3! upon which are supported a'pair of posts 32 to'w'hich is pivotally mounted,

by the bearing-studs 33, a frame '34 to Whichtis adjustably connected the mount 35 carrying the prism 8, as by means of resiliently opposed studs 36. The frame 34 is biased in a clockwise direction as viewed in Figure 4 by a tension spring 31 and has an integral arm 38 carrying a ball 39 engaging the square end surface of a vertical operating rod 4| guided for reciprocable movement in. openings in the head 3| and in a lower flange 42 (Figure 3) rigidly connected to the lower portion of the tube 29 Referring to Figure 3, into the lower end of the rod 4| there is adjustably threaded a head 43 having a square bottom surface engaging a ball 44 carried by an arm 45 rigid with a plate 46 mounted upon a plate like hub 41 integral with a rotatable shaft 48 which is of conical form and mounted in a conical bearing 48 (Figure '1'). The plater46 is adjustably mounted on the hub 41 through a plurality of locking studs threaded in the hub 4'! and with the openings through the plate 45 slotted so as to permit variation of the effective length of the arm 45. A pair of adjusting studs 52 are threaded into the plate 48 and bear upon a reduced extension 53 of the hub 48.

As shown in Figure 7, the shaft 48 passes through a dividing wall 54 of the main body portion 2 and carries at the end opposite the hub 41 a sector 55 rigidly mounted on the shaft 48 by the nuts 56. a

Referring to Figure 6, the sector 55 meshes with a worm gear 5'l mounted upon a shaft 58 extending to the exterior of the body portion of the sextant and carrying the operating knob 3.

Provision is made for a limited rotative movement of the shaft 58 about a transverse axis through the ball portion 59 setting on one side in the socket 5| and spring biased therein by engagement at the opposite side with seats 62, 53 biased against the ball portion 59 by the springs 64 and 65 disposed against the stops 66, 81. The inner end of the shaft 58 is journalled in a floating bearing 68 biased upwardly, in a direction to maintain the Worm and sector engaged, by means of a spring .59 surrounding a limiting stud threaded into a fixed part I2.

As shown in Figures 6 and 8, the shaft 58 terminates in acoupling l3 engaging the operating mechanism of an averager indicated generally at 14. This averager may or may not be used with the sextant construction and as it forms no part of the present invention it has not been illustrated herein. Its function, as is well known in the art, is to provide for an instrument reading which is an average taken over a continuous period of time. Without the averager, the instrument is fully operative in the same manner as other sextants with the observer taking either a single observation or a plurality of observations in quick succession from which an average is taken.

1 As shown in Figures 6 and 8, there is pinned to the shaft 56 a bevel gear meshing with a bevel gear 16 at one end of a shaft 11 pivoted in an arm 18 mounted on the bearing 58. To the end of the shaft 11 is pinned a coupling 19 meshing through a star plate 8| with a coupling 82 on the counter 5. As this counter is a standard commercial item, it is shown only in elevation in the drawings.

Referring to Figure 3, it is seen that the reflecting mirror 21 is disposed within a container 83 having a spherical inner chamber filled with a damping liquid in which the mirror 2'! and its depending skirt 84 are disposed, the mirror having a pivot 85 seating in a cup seat 86 carried by a post 81. This pendulous mirror is disclosed and claimed in applicants co-pending application Serial No. 31,928, filed June 9, 1948, for Horizontal Reference, now Patent No. 2,557,340, issued June 19, 1951. r

The shaft 58 is provided with a gear 18 mesh- V strument is not only smaller but requires but a small opening through the aircraft skin. With the adjustment of the effective length of the rod 4| by rotation of the head 43, and of the length of the arm 45 by adjustment of the plate 46 on the hub 41, the angular position of the prism 8 and the reading on the counter 5 may be brought into proper relationship within allowable limits over the field of operation of the prism. The distance between the axis of the shaft 48 and the center of the ball 44 will be substantially the same as the distance between the axis of rotation .of the prism 8 and the center of the ball 39.

The adjustment is ordinarily made by optical collimation to give the correct readings on the counter for the angular positions of the index prism. Ordinarily the effective length of the rod- 4l is first adjusted by the head 43 to secure opposite sign variations on the counter for zero and 90 positions of the prism when the counter and prism are in conformance for 45". Thereafter the length of the arm 45 is adjusted byloosening the screws 5| and rotating the screws 52 in opposite directions until the prism and counter are in conformance at zero and 90 as well as at 45.

The foregoing adjustment of the length of'the rod 4| and of the arm 45 also takes care of cumulative error which might occur between the sector 55 and the worm gear 51. Hence, this gearing does not have to be as exact as in the case where a cumulative error would be added into the instrument reading.

The adjustment above referred to can further reduce any error which might arise due to the fact that the planes of the prism are not at the exact 45 angle.

The ball mount 59 and the spring biased bearing 58 shown in Figure 6 maintain the worm and sector in engagement and take care of variations in the relative height of the gears. The limiting stud H is normally set to take care of the highest gear condition and thereafter the spring 59 will move the bearing 68 to maintain ,the worm and sector in engagement for lower'gear positions. 1

While a particular preferred embodiment of the invention hasbeen illustrated in the'drawings, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the followin claims. I

What is claimed is: r

1. In a periscopic sextant, a main body portion carrying an eye piece for viewing the image of an observed object, an elongated periscopic portion projecting from said main body portion, an index prism at the end of said periscopic portion, an optical system in said periscopic and main body portions for producing an image of an object observed through said index prism, a

horizontal reference with respect to which the image of said object is observed, means for indicating the angular position of said index prism, and manually operated means interconnecting said index prism and said angle indicating means for effecting rotation of said index prism and for indicating its angular position and the angular height of said observed object, said manually operated means including a manually rotatable first arm pivoted in said main body portion, a second arm pivotally mounted near the outermost end of said periscopic portion, said index prism connected to said second arm, a spring means biasing said index prism in one direction, both of said arms having spherical surfaces on oppositely directed sides thereof mounted so as to be directed toward each other, adjustment means provided on the pivotal mounting of said first arm so that the effective lengths of said arms can be brought into substantial conformance, a reciprocable rod interconnecting said arms, said rod having right angle fiat end surfaces engaging said spherical surfaces on said arms so as to engage said spherical surfaces tangentially at all times, whereby rotation of said first arm not only effects rotation of said second arm and index prism through reciprocation of said rod but also positions said angle indicating means.

2. In a periscopic sextant, a main body portion carrying an eye piece for viewing the image of an observed object, an elongated periscopic portion projecting from said main body portion, an index prism at the end of said periscopic portion, an optical system in said periscopic and main body portions for producing an image of an object observed through said index prism, a horizontal reference with respect to which the image of said object is observed, means for indicating the angular position of said index prism, and manually operated means interconnecting said index prism and said angle indicating means for effecting rotation of said index prism and for indicating its angular position and the angular height of said observed object, said manually operated means including a manually rotatable first arm pivoted in said main body portion, said pivoted arm having a pair of positioning screws for adjusting the effective length of the arm, a second arm pivotally mounted near the outermost end of said periscopic portion, said index prism being connected to said second arm, spring means biasing said index prism in one direction, both of said arms having spherical surfaces on oppositely directed sides thereof mounted so as to be directed toward each other, said positioning screws enabling the effective lengths of the arms to be brought into substantial conformance, a reciprocable rod interconnecting said arms, said rod having right angle flat end surfaces engaging said spherical surfaces on said arms so as to engage said spherical surfaces tangentially at all times, whereby rotation of said first arm not only effects rotation of said second arm and index prism through reciprocation of said rod but also positions said angle indicating means.

VICTOR E. CARBONARA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 725,570 Lake Apr. 14, 1903 826,155 Dudley July 17, 1906 988,279 Moller Mar. 28, 1911 1,178,474 Becker Apr. 4, 1916 2,229,855 Liebmann Jan. 28, 1941 2,280,798 Crane et a1. Apr. 28, 1942 2,305,437 Meyers et al Dec. 15, 1942 2,378,282 Brueske June 12, 1945 2,413,017 Willcox Dec. 24, 1946 2,484,072 Castedello Oct. 11, 1949 FOREIGN PATENTS Number Country Date 544,217 Great Britain Apr. 2, 1942 

